Optical fiber is conventionally employed to guide and propagate optical waves along or between fiber ends. A common implementation involves fitting or coupling one or both ends of an optical fiber with a light source, such as an LED or laser diode. Traditional optical fiber, aka “normal” optical fiber, keep photons of a light source within the optical fiber, typically by encasing a cylindrical core of a dielectric material with cladding. The photons remain within the fiber optic because the refractive index of the core is greater than that of the cladding.
In contrast, a diffusive optic fiber allows some photons to escape the fiber optic core through intentional imperfections in the cladding. The fiber optic may then serve as a thin line light source, when one or both ends of the optical fiber are fitted with a light source. The cladding imperfections may be formed by any of several means, such as by surface imperfections on the fiber surface or by material imperfections of the fiber (e.g. as provided by the Corning Fibrance™ product). With increasing randomness and quantity of imperfections, the illumination pattern becomes uniformly omnidirectional.
One unnoticed, yet important, feature of diffusive optic fiber is the ability of external light to enter the diffusive fiber optic (by way of the aforementioned imperfections) in addition to light escaping or departing the diffusive fiber optic. Such a corollary is provided through the optical path reverse principle. If a particular diffusive optic fiber produces a uniformly omnidirectional illumination, then the same diffusive optic fiber will also receive optical signals, energy or photons omnidirectionally from the ambient or external environment into the diffusive optical fiber through the fiber surface (e.g. by way of imperfects in the cladding). In recognition of this discovery, a diffusive optical fiber (aka optical waveguide or fiber waveguide) may be used as an omnidirectional ambient/external light sensor. In such a configuration, optical detectors could be placed at fiber ends to detect optical signal and/or energy from the surrounding environment. The optical energy or signal received may be any optical band, to include visible and infrared; IR sensing may be particularly suited to sensing of fires.
Techniques for fiber optic light sensing and communication are provided. Specifically, systems and methods to provide diffusive optical fiber sensors and communication devices and methods of use are disclosed.
By way of providing additional background, context, and to further satisfy the written description requirements of 35 U.S.C. § 112, the following references are incorporated by reference in their entireties: U.S. Pat. Pub. Nos. 2007/0031089 to Tessnow and 2002/0186921 to Schumacher, U.S. Pat. No.6,272,269 to Naum and U.S. Pat. No. 7,621,677 to Yang, and “Use of Diffusive Optical Fibers for Plant Lighting” by Kozai, as found in “International Lighting in Controlled Environments Workshop,” Tibbitts, Editor, NASA-CP-95-3309 (1994).